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And that could mean ever fewer people than expected might cast ballots in these elections.

"Any confusion from voters ... can dramatically affect turnout.," said Brandon Rottinghaus, a political science professor at the University of Houston. "Many voters won’t be able to keep the elections straight and may assume that they can only vote in one."

Anyone who doesn’t have one of those IDs, and can’t get one before voting, may show another form of identification and fill out a "reasonable impediment declaration."

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Election officials have long suggested that people review sample ballots online before heading to the polls to vote.

And they suggest people check on their polling place before heading out to make sure it hasn't changed, especially because with two elections in May, voters could end up at two different polling sites in one month. Information about both issues can be found online at access.tarrantcounty.com/en/elections.html.

And if you are voting by mail, you might have both ballots at your home at the same time, Garcia said.

Make sure to return each ballot in the envelope that came with it. Don't mix up the envelopes or put both ballots in one envelope, he said.

"Put them in the right envelopes," Garcia said. "It's extremely important. Your envelope helps us track that you've voted."

Anyone with questions about one or both elections should call the Tarrant County Elections Office at 817-831-8683. Voters statewide may call the Secretary of State’s Office at 1-800-252-VOTE.